Can the headlamps(vs. the entire headlight unit)be easily replaced on a '91 911? on 1991 Porsche 911

I'm looking to replace the lamps (internal to the headlight unit) only, not the entire headlight unit

Asked by for the 1991 Porsche 911
2 answers 2 comments
This video should help you http://www.youtube.com/watch?v=D65x8G1f6AI
Thanks, but on my '91 911 the rubber plug on the trunk sidewall appears to be sealed. Do I need to push through this somehow?
Wow, this headlight unit must be the EASIEST one to replace...
OK. Now how?